You don't need a background check for FAA glider or balloon training. The TSA trigger for a background check is training for (1)the first FAA certificate (2)a multiengine rating (3)an instrument rating (4)a type rating. The ATP is a glorified IR so if your private is VFR only you'll need the check or if your private is SE and you want a ME ATP you'll need the check. Also, if your private is a 61.75 cert based on a foreign license you've never had training for a FAA cert so this would be your initial certificate and require a background check.